Here is an excerpt from an excellent article written by Eric Geiger for MinistryStrategies.com.
Typically pastors or staff persons are hired to minister to people. The number of children increases, so the solution is another staff person. The number of sick people is on the rise; therefore, someone is hired to visit people in the hospitals. The typical approach is both illogical and unbiblical. The view is illogical because a church will never be able to afford to hire the entire ministry away. The view is unbiblical because it violates the essential doctrines of the priesthood of believers and spiritual gifting.
– Brad